Parachute canopy deflation apparatus



PARA CHUTE CANOPY DEFLATION APPARATUS Filed Jan. 12, 1968 ,5 2 FIG. 5

INVENTOR. 6 warm? 6. BOCKELMANN United States Patent 3,434,681 PARACHUTE CANOPY DEFLATION APPARATUS Victor G. Bockelmann, El Centro, Calif., assignor to the United States of America as represented by the Secretary of the Navy Filed Jan. 12, 1968, Ser. No. 697,455 Int. Cl. B64d 17/02; B63b 21/48 U.S. Cl. 244-145 ABSTRACT OF THE DISCLOSURE The deflation apparatus is formed of a number of pockets disposed on the external surface of the parachute canopy and preferably located on alternate gores at the skirt portion of the canopy with the opening of each pocket facing upwardly away from the skirt toward the apex of the canopy. If the parachute lands on a body of water, the pocket scoop the water to anchor the chute, deflate it and prevent its being blown along the water surface. Such pockets are known in the art although previous pockets, due to the unrestricted length of their pocket openings, presented seriou problems. The present pockets instead of having a completely open and unrestricted mouth portion along the entire open edge of the pocket, utilize straps securing the central portion of each pocket to the canopy. The straps, which are specially formed and specially secured, provide suflicient strength and rigidity to the pockets to avoid ripping of their seams and, particularly to prevent them from being inverted or pulled inside out so as to spill the trapped water.

3 Claims The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

The present invention relates to parachutes and particularly to parachutes intended for use over water surfaces for safely lowering personnel or equipment.

US. Patent 3,167,279 issued Jan. 26, 1955 to Brian Richard Arnold Reflell is exemplary of the prior art toward which the present improvement is directed. The Reifell parachute employs the previously described pockets, each of which extends in an unrestricted manner the entire length of each gore of the canopy. Two principal diflicultie have been experienced in the use of parachutes of this type and both of the defiiculties are due to the fact that the open mouths of the pockets are unrestricted in their extent. In use, such pockets have a tendency to be pulled inside out as the main part of the canopy collapses and, of course, any such inversion permits the trapped water to spill out to destroy the anchoring effect. Although this problem might be resolved by making the pockets themselves considerably deeper, such a solution is not a desirable one since any increase in the size of the pocket adds weight to the parachute and weight is a significant design factor in this art.

The other difliculty is the tendancy of these unrestricted pockets to rip or tear along their side seams. As will be appreciated, the weight of the water in the pocket coupled with the force exerted by the wind places the stitching of the seams of the pocket in shear and this shear force tends to produce failures in high wind conditions. Such failures are not too surprising when it also is considered that the individual stitches of the seams are loaded-up locally one stitch at a time and, further, that the fabric to which the pockets are sewn is initially weakened by the stitch perforations.

THE OBJECTS It is therefore, a primary object of the present invention to provide a personnel or equipment parachute having canopy deflating pockets, the pockets being capable of assuring retention of the trapped water to assure the maintainance of the anchoring force needed to produce the canopy deflation.

A further object is to provide a parachute similar to that described in the previous object, the pockets of the parachute being so arranged as to distribute the forces tending to produce failures by the tearing or ripping of the seamed portions of the pockets.

Yet another object is to provide a parachute of the type under consideration, the pockets having sufiicient rigidity and strength and also utilizing a minimum amount of fabric so as to minimize the total parachute weight.

STATEMENT OF THE INVENTION The objects of the present invention are achieved principally by utilizing a narrow restraining strap which secures the center portion of each of the mouth portions of the pockets to the gore of the canopy on which the pocket is formed. Preferably, to minimize weight, the pockets, which usually have a depth of about 10 inches, are formed on alternate gores of the canopy and the straps are formed of 5-inch strips of nylon tape specially secured between the canopy and the pockets. As will be readily appreciated, the straps restrict the otherwise open mouth portion of each pocket sufiiciently to prevent the pockets from inverting and causing the trap water to spill out. The length of the straps is a significant factor since excessive lengths may permit an inversion of the pockets while undue shortness will limit the volume of the water capable of being trapped in each pocket and thus limit the anchoring effect. In addition to avoiding pocket inversion, the straps also accept a significant portion of the shear forces tending to rip the seams. In other words, the forces normally exerted stitch by stitch on the vertical seams at the edges of the pockets are redistributed so that a substantial portion is borne by the straps. Preferably, as will be described subsequently, the end portion of the straps which engages the center portion of the pocket are double looped and specially sewn to the pocket to provide additional strength.

THE DRAWINGS The preferred embodiment of the invention is illustrated in the accompanying drawings of which:

FIG. 1 is a side elevation of a parachute canopy having pockets formed on its alternate gor es;

FIG. 2 is a somewhat schematic view of a fragmentary portion of the parachute canopy in a water-scooping disposition;

FIG. 3 is an enlarged view showing one of the pockets illustrated in FIG. 1; and

FIGS. 4, 5, and 6 are sections taken along lines 4-4, 5-5, and 6-6 of FIG. 3.

Referring to FIG. 1, the illustrated parachute is of a conical type although other types are equally adaptable for present purposes. As shown, a parachute canopy 1 is formed of a series of gores 2 which, in the usual manner, are sewn one to the other along radial seams 3 and 4. The canopy has an apex portion 6 at which the gores converge to a point, and a skirt portion 7 which can be defined as the outer peripheral edge portions of the joined gores. Suitable parachute lines (not shown) are connected to the canopy and, of course, the function of the apparatus is to lower personnel or equipment safely and gently onto surface which may be land or water.

The present parachute is particularly adapted for landings on water and, for this reason, it is provided with a plurality of pockets 8 formed in a manner to be described with outwardly facing mouths 9 (FIG. 2) enabling the pockets to scoop water in the manner illustrated in FIG. 2.

Entrapment of the water in pockets 8 is intended to anchor the parachute and prevent the wind from blowing it across the surface of the water. If the chute is driven across the water there is considerable danger to air crew members particularly if the fall has resulted in any injury. Water anchors of this type also are desirable when the chute is used to land equipment needed by a disabled vessel or the like. For example, it may be desirable to drop bilge pumps or the like to a disabled vessel and, of course, it is most essential that they be dropped as closely as possible to the vessel. If the wind should blow the chute and its pump away from the vessel, the drop is a failure.

Pockets 8 may be formed on each gore of the chute, although, for present purposes, it has been found that the provision of pockets on alternate gores is effective for water-anchoring purposes and also is desirable because of reduction in weight. To minimize weight, it is desirable to reduce the size of the pockets to a point at which the volume of trapped water is just enough to provide an effective anchor.

The manner in which the pockets are secured to the gores of the canopy is best seen in FIGS. 3 and 4 where it may be seen that each pocket has its bottom edge 11 seamed to the outer peripheral extent of its gore. More specifically, both the pocket and the gore, which usually are formed of a fabric such as nylon, are folded back upon themselves and stitched with double rows one to the other. Sides 12 of each pocket are secured to radial seams 3 and 4 of the gores in the manner shown in FIG. 5. Here again, the side portions are folded back upon themselves and sewn to the radial seam by two row stitching. Upper edge portion 13 (FIG. 3) of the pockets are left open except for their restraining straps to be described. With such an arrangement the pockets have the previously-mentioned open mouth 9 to scoop the water and cause deflation. To further enhance the scooping action the pockets normally bulge outwardly of the canopy, this effect being achieved by making upper edge 13 of the pocket of greater length than the corresponding underlying distance between radial seams 3 and 4. It will be appreciated that the added length produces the desired bulge.

As already indicated, the prior art pockets, in which the outward bulge of the pockets is unrestricted, are subject to failure due to pocket inversion or to tearing at their side seams. Inversion occurs because of the length of their unrestricted mouth portions coupled with the fact that the collapsing action of the canopy provides sufficient fabric to permit bottom edge 11 to be forced to an inside-out disposition. If the pockets were shorter this undesirable result might be avoided. However, pockets must have sufficient volume to anchor the chute and, further, practical design requires the pockets to be coextensive with and seamed to the gores. Further, the gores of most chutes are equal in circumferential length at the skirt portion of the canopy so that the pockets on most canopies have the same length. For example, although a 28 foot flat circular canopy has 28 gores, a 26 foot conical type has 22 gores and the distance between its gore seams at the skirt is the same as that of the 28 foot canopy. Thus, most parachutes formed with unrestricted pockets are subject to failure due to the inversion of the pockets and the spilling of their entrapped water.

The other difficulty with unrestricted pockets is that they have been found to rip at the side seams 12 and, of course, a failure of this type again permits the water to spill out. The tearing or ripping is due in part to the fact that any seamed edges are perforated so as to be initially weakened. Further, the stitches of the side seam are subjected to a very substantial load and the load is imparted to the stitches one at a time commencing with the uppermost stitch. The load, as will be appreciated, is due to the drag force of the canopy as the wind attempts to pull it along the surface of the water.

A principal feature of the present invention resides in the use of restraining straps 15 show in FIGS. 3 and 6. Most suitably, these straps are formed of nylon tape approximately five inches in length secured to both the canopy and the pocket in the illustrated manner. In particular, inner end 16 of the strap is folded upwardly as shown in FIG. 6 and stitched to the canopy with two rows of stitching 17. Other types of stitching of this particular portion may be used, although the two rows of stitching provide adequate strength. At its outer end, nylon tape 15 is formed into a reverse bend 18 that fits flushly against the exterior wall of pocket 8 the tape, then being folded over the top edge of the pocket and downwardly. This particular three-ply construction usually is needed to permit the tape to absorb the forces acting on the pocket without ripping. Further, it is desirable to bar tack the three-ply folds to the center of upper edge blank of the pocket. At its other end, tape 15 is secured to the center of its gore.

The use of restraining tapes 15 effectively avoids the difficulties which have been previously described. In the first place, the tapes render the pockets more rigid by limiting the extent to which the upper edge of the pocket can be forced away from the underlying canopy. As already stated, the tapes preferably are about five inches long although the length of the tape may vary with the depth of the pocket and with other dimensions of the chute. A five inch tape is suitable for a pocket having a depth of about ten inches and, in practice, it also has been found that most effective restraining action is achieved when this one to two ratio is preserved. Obviously, the restraining action of the tape also acts to limit the maximum volume to which the pocket can expand and, if the volume is limited to an excessive degree, the entrapped volume of water may become insufiicient to provide a suitable anchor. Consequently, there is an optimum size for the straps and as indicated this size will preferably be about one-half the depth of the pocket.

Other advantages inherent in the use of restraining straps 15 stem from the fact that these straps absorb a substantial part of the drag force which otherwise acts entirely on the side seams of the pockets to produce eventual tearing of the steams. The restraining straps are strengthened by the three-ply construction shown in FIG. 6. It further is to be noted that very substantial forces are applied to the outer ends of the tapes when the chute first opens during a drop so that the three-ply construction again resists tearing during the drop.

The advantages of previous pockets are fully retained even to the extent of retaining the stabilizing action which these pockets provide as the chute is falling through the air. As may be known, such pockets are beneficial in dampening oscillations since any tendency of one side of the chute to drop excessively is counteracted by a pocket on the opposite side becoming filled with air.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that the invention may be practiced otherwise than as specifically described.

I claim:

1. Parachute apparatus comprising a plurality of outwardly-tapering fabric gores extending from an apex to a skirt portion of the parachute to form a canopy,

radial seams securing said gores one to another,

a plurality of pockets arranged circumferentially on said skirt portion,

each of said pockets being formed of a length of fabric secured at its ends to said gore seams and along its bottom edge to the peripheral edge of said skirt and said pockets being arranged on the exterior surface of said canopy each with an open mouth portion facing upwardly of the canopy toward said apex whereby said pockets are capable of trapping water and anchoring the parachute when it drops onto a water surface, the upper edge of each pocket being greater in length than the distance between the gore seams to which it is attached for enlarging said mouth opening, and a fabric strap securing the central portion of the upper edge of each pocket to the underlying canopy gore, said straps being sufiiciently long to assure a pocket volume capable of anchoring said canopy and being sufliciently short to avoid inversion of the pockets when the canopy collapses on the water. 2. The apparatus of claim 1 wherein the length of fabric strap is approximately one-half the depth of said pocket from said open mouth portion to said bottom edge. 3. The apparatus of claim 1 wherein said fabric strap is secured to said pocket with 10 MILTON BUCHLER, Primary Examiner.

a three-ply folded con- RICHARD A. DORNON, Assistant Examiner.

U.S. Cl. X.R. 15 114-209 Disclaimer 3,434,68L-Vz'etor G. Boekelmann, El Centro, Calif. PARACHUTE CANOPY DEFLATION APPARATUS. Patent dated Mar. 25, 1969. Disclaimer filed Jan. 26, 1972, by the assignee, United States of America as regwesented by the Secretary of the Navy. Hereby enters this disclaimer to claims 1, 2 and 3 of said patent.

[Ofiicz'al Gazette July 25, 1.972.] 

